Also, due to my practical experience of the Buddhadhamma, I have seen pettas, asuras, and the devas of Catumaharajika, who are "tree spirits" and who also live in lakes and springs, and I have talked with and interacted with them. This I think means that I know at least of the Pettivisaya, Asurayoni, and Catumaharajika planes from personal experience.
Sometimes no Buddhas arise in the world. Sometimes they do. When it happens, it is for the welfare and happiness of men, out of compassion for all creatures. For a long, long time he has been working to become a Buddha. He met other Buddhas along the way. And after his long striving he attains his final life, yet not without showing everyone else how to get there.